North American Network Operators Group Date Prev | Date Next | Date Index | Thread Index | Author Index | Historical Re: backbone routers' priority settings for ICMP & UDP
On Wed, 4 Feb 1998, Dave Siegel wrote: > Extremely weak metaphore, since a source quench indicates there weren't > enough buffers available to send your packets. > > Now, if the freeway was full, and cars started dropping out of the space/time > continuum, that'd be more like a source quench. ;-) The freeway would call > your wife at home and say "sorry, but your husband didn't make it to work > because the freeways were too full." If wife runs correct a correct > TCP implementation, she would know to initiate "slow start" and would > send out her husbands at a slower rate until she gets a feel for how > bad the traffic is. ROFL, nice extension. But this is not true because, as you say below, gateways don't source quench anyore. > > > One then > > wonders how well Win95 implements source quench, if at all. > > Which side of the implementation do you mean? as a client, or as a gateway? > I suppose it doesn't really matter. Since source quenches are not supposed > to be used on routers anymore, the expectation of receiving a source > quench on a large network (like the Internet) is a bad one, so the TCP > implementations have to implement congestion controls through other means > anyhow. As a client, of course, since end-to-end source quench is the only alternative available. And consider the near future scenario where a user with a cable-modem connected via Ethernet to their nice new NC (with cheapest bus design possible to contain costs) has requested a URL from a <insert whomping fast server here> connected via OC-3 to the Internet. It seems likely a source quench will come in handy to provide flow control. > > TCP/IP Illus. Vol. I by W. Richard Stevens has a pretty good explanation > of what source quenches are. Don't have Mr. Stevens handy, but from RFC777 (1981!), when both types of source quench were defined: ...A destination host may also send a source quench message if datagrams arrive too fast to be processed. The source quench message is a request to the host to cut back the rate at which it is sending traffic to the internet destination. This is what I was getting at. Flow control versus congestion control. ------------------------------------------------------------------- Scott Whyte 408.527.5713 |Any opinions expressed herein are Network Supported Accounts (NSA) |mine and not cisco's... CCIE 3340 | | "Eschew Obfuscation"
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